Lycopene — a carotenoid antioxidant that gives fruits and vegetables like tomatoes and watermelon a pink or red color — is one nutrient you'll want to be sure you're getting enough of.Lycopene's antioxidant activity has long been suggested to be more powerful than other carotenoids such as beta-carotene, and research has even revealed it may significantly reduce your stroke risk (while other antioxidants did not).Lycopene has been shown to have potential anti-cancerous activity, likely due to its antioxidant properties. Studies have shown that people with a diet high in lycopene from tomato-based foods have a lower risk of certain cancers, particularly prostate cancer.However, lycopene is one example of a nutrient that becomes more bioavailable when it's cooked. Research shows that cooking tomatoes (such as in tomato sauce or tomato paste) increases the lycopene content that can be absorbed by your body.It also increases the total antioxidant activity. In one study,4 when tomatoes were heated to just over 190 degrees F (88 degrees C) for two minutes, 15 minutes, and 30 minutes:

So while tomatoes are healthy to consume raw, it's also wise to consume them cooked as well. You could try a cooked salsa or make your own tomato sauce at home… if you opt for a store-bought variety, make sure it comes in a jar, not a can.NOTE: You're best off avoiding canned tomatoes and tomato sauces, as can liners tend to contain potent estrogen mimics such as bisphenol A (BPA), which is a toxic endocrine-disrupting chemical.

Storing Your Lettuce Wrong

Do you store your lettuce leaves whole? You may be better off tearing them before storing them in your refrigerator. When lettuce leaves are torn, a boost of protective phytonutrients are produced.As long as you eat the lettuce within a couple of days, you'll be able to take advantage of this extra phytonutrient content in the torn lettuce.

Boiling Your Vegetables

Do you boil vegetables like spinach? This allows valuable nutrients like vitamin C to leach out into the water. The difference in nutrient content can be dramatic before and after boiling.For instance, after 10 minutes of boiling, three-quarters of the phytonutrients in spinach will be lost to the cooking water. While this isn't as much of an issue if you're making soup, in which you'll be consuming the water along with the nutrients, if you're looking to prepare a vegetable only, you're better off steaming or lightly sautéing.

Cooking Garlic Without Letting It Rest

Garlic contains the precursors to allicin, which is one of the most potent antioxidants from the plant kingdom. In fact, researchers have determined that sulfenic acid, produced during the rapid decomposition of allicin, reacts with and neutralizes free radicals faster than any other known compound—it's almost instantaneous when the two molecules meet.Garlic technically does not contain allicin, but rather, it contains two agents in separate compartments of the clove that react to form the sulfur-rich compound allicin when the plant needs it: alliin and an enzyme called allinase. So, what makes them react?Garlic has a robust defense system to protect itself from insects and fungi. It enzymatically produces allicin within seconds when it is injured. The crushing of its tissues causes a chemical reaction between the alliin and the allinase, and allicin is produced—nature's "insecticide."This is what makes garlic such a potent anti-infective, as well as what produces that pungent aroma when you cut into it. Allicin is quickly deactivated by heat. Just two minutes on the stovetop or one minute in the microwave will basically eliminate any useful allicin from the garlic.However, if you let chopped garlic sit for 10 minutes before exposing it to heat, the enzyme that creates allicin will have time to finish working, and your finished dish should have a much higher allicin content. That being said, allicin is short-lived, lasting less than an hour. So once you've crushed your garlic and let it rest, try to consume it as quickly as possible. Better still, use a garlic press instead of a knife.Eating Potatoes Right After Cooking Them

I don't recommend eating white potatoes often, as their simple sugars are rapidly converted to glucose that raises insulin levels and can devastate your health. However, if you do choose to eat them at least chill them for about 24 hours after cooking. This converts the starch into a type that's digested slower, and turns this high-glycemic vegetable into a low-glycemic one.

Cutting Carrots Prior to Cooking

Resist the urge to chop up your carrots before adding them to soups and casseroles. Research suggests that keeping the carrots whole, and cutting them up after they're cooked, helps retain nutrients. Also, like tomatoes, carrots may be better for you cooked than raw. Cooking helps break down the cell walls so your body has an easier time absorbing nutrients. Further, one study found that cooked carrots had higher levels of beta-carotene and phenolic acids than raw carrots, and the antioxidant activity continued to increase over a period of four weeks.

Buying Broccoli Florets Instead of a Whole Head

Broccoli is one of the healthiest, cancer-fighting veggies you can eat. But it's also surprisingly perishable. One study found that broccoli can lose 75 percent of its flavonoids and 80 percent of its beneficial glucosinolates just 10 days after harvest. When the broccoli was cut into florets, the rate of antioxidant loss doubled, so choose fresh, locally grown broccoli in whole-head form for maximum nutrition.